1. Technical Field
The present invention relates to a liquid-crystal display device provided with liquid crystals and to an electronic apparatus including the liquid-crystal display device provided with liquid crystals.
2. Description of the Related Art
There have been developed systems (modes) for driving liquid crystals, including a liquid-crystal driving system that uses an electric field generated in a longitudinal direction between substrates, that is, a longitudinal electric field. Examples of a liquid-crystal display device that drives liquid crystals using a longitudinal electric field include, but are not limited to, longitudinal-electric-field liquid-crystal display devices provided with a twisted nematic (TN) system, a vertical alignment (VA) system, an electrically controlled birefringence (ECB) system, etc. As disclosed in Japanese Patent Application Laid-open Publication No. 2008-52161 (JP-A-2008-52161), there has also been developed a liquid-crystal driving system that uses an electric field generated in a direction parallel to substrates (lateral direction), that is, a lateral electric field. Examples of a liquid-crystal display device that drives liquid crystals using a lateral electric field include, but are not limited to, lateral-electric-field liquid-crystal display devices provided with a fringe field switching (FFS) system, an in-plane switching (IPS) system, etc.
In the IPS mode, a first electrode and a second electrode are provided on the same layer, and an electric field is generated mainly in a direction parallel to the substrate surface. This configuration makes the electric field unlikely to be generated in an area above the first electrode, thereby making liquid-crystal molecules in the area unlikely to be driven.
In the FFS mode, a pixel electrode and a common electrode overlap in a direction perpendicular to the substrate surface with a dielectric film interposed therebetween. This configuration generates an electric field extending mainly in a direction oblique to the substrate surface or a parabolic electric field (also referred to as a fringe electric field). As a result, liquid-crystal molecules in an area above the pixel electrode are likely to be driven. In other words, the FFS mode can provide a higher aperture ratio than the IPS mode does.
The lateral-electric-field liquid-crystal device generates an electric field between the first electrode and the second electrode in a direction parallel to the substrate, thereby rotating the liquid-crystal molecules in a plane parallel to the substrate surface. The liquid-crystal device uses a change in the light transmittance corresponding to the rotation of the liquid-crystal molecules, thereby performing display. Such lateral-electric-field liquid-crystal display devices are required to achieve a higher response speed of the liquid-crystals.
Japanese Patent Application Laid-open Publication No. 2013-109309 (JP-A-2013-109309) discloses a liquid-crystal display device having a higher response speed of liquid crystals than the liquid-crystal device disclosed in JP-A-2008-52161 does.
The liquid-crystal device disclosed in JP-A-2013-109309 has a higher response speed of liquid crystals. In the liquid-crystal device, however, the rotation direction may possibly be unstable at a boundary portion between pixels, resulting in variation in the orientation of the liquid crystals.
For the foregoing reasons, there is a need for a liquid-crystal display device and an electronic apparatus including the liquid-crystal display device that achieve a higher response speed and higher orientation stability of liquid crystals at a boundary between pixels and have higher in-plane display quality.